New Delhi, India (CNN) – The company’s director said, Thursday, that a fire broke out in the building of the world’s largest vaccine manufacturer, killing five people, and that it would not affect vaccine production.

The Serum Institute of India (SII) fire was brought under control in the western city of Pune on Thursday, although the cause is still under investigation, according to Murleidhar Mohol, the city mayor.

Mohul said four people were rescued from the six-story building but five others died. They are believed to be construction workers as the building was still under construction at the time of the fire.

Videos and images showed black smoke billowing from the building at the company compound. Muhl said 15 units from the municipality and the fire department worked to put out the fire.

He added that initial investigations indicate that “during the construction of the building, some welding work may have caused a fire.”

Fire brigade chief Bonnie Prashant Runby said Friday that the fire started on the second floor. While the firefighters were working to put out the flames, the fire spread to another location. The second fire was extinguished at 4:15 p.m. local time by 50 firefighters and employees. Ranbis said they are still investigating the cause of the fire.

Unfortunately, we learned that there was some loss of life in the accident. We are deeply saddened and extend our deepest condolences to the families of the deceased, ”SII CEO Adar Poonawalla wrote Thursday.

SII, the world’s largest vaccine manufacturer, is partnering with the University of Oxford and AstraZeneca to produce the Coffeeshield vaccine. In December, the company said it was producing between 50 to 60 million doses of Covishield per month, with production increasing to 100 million doses in January or February.

Serum Institute in India is a family-run business that Poonawala’s father started 50 years ago to offer cheaper vaccines to the masses. It aims to produce hundreds of millions of coronavirus vaccines not only for India, but also for other developing countries.

In a tweet, Bonawala said that although “some floors have been destroyed”, the production of the Coffeeshield vaccine would not be affected.

“I would like to assure all governments and the public that there will be no production loss from Coffeeshield due to the multiple production buildings I have kept in reserve to deal with such emergencies,” he said.

Cyrus S. Bonawala, SII Chairman and Managing Director, said in a statement that the fire broke out at a facility that was bound in the Mangri Special Economic Zone. He said it was a “very sad day” and that the company would provide 2.5 million rupees (34,000 US dollars) for each of the victims’ families.

Indian Prime Minister Narendra Modi tweeted on Thursday: “I mourn the loss of life due to an unfortunate fire … At this sad hour, my thoughts are with the families of those who lost their lives. I pray to God that the wounded heal as quickly as possible.”